How to fund AccountId32?

Question

I want to deliver some test where in part of the task is to create accounts and deposit them. I do it in the code below:

let account_id_bytes: [u8; 32] = [0u8; 32];
let account_id_1: AccountId32 = AccountId32::new(account_id_bytes);

Now I want to fund account_id_1 like:

Balances::force_set_balance(RuntimeOrigin::root(), account_id_1, 100).unwrap();

Function force_set_balance expects u64, but I have AccountId32 type. How to fund the account right? My guess is that conversion AccountId32 to u64 is not the best approach. Appreciate any tips.

Answer 1

You have to remember that the Substrate runtime is generic over many types, including the AccountId.

Function force_set_balance expects u64

If this is the case, then the context in which you are calling force_set_balance has been configured for AccountId = u64. This is usually the default configuration in tests, which is my guess where this is happening.

You can adjust your configuration to make AccountId = AccountId32 instead, and that will fix this problem.

You can find an example of that in the Polkadot integration tests: https://github.com/paritytech/polkadot-sdk/blob/master/polkadot/runtime/common/src/integration_tests.rs

Here you can see:

use sp_runtime::AccountId32;

type AccountId = AccountId32;

This being used in the configuration for frame_system:

impl frame_system::Config for Test {
    type AccountId = AccountId;
    // ...
}

And some helpers to make generating unique AccountId32 more easy:

fn account_id(i: u32) -> AccountId32 {
    let b4 = i.encode();
    let b32 = [&b4[..], &b4[..], &b4[..], &b4[..], &b4[..], &b4[..], &b4[..], &b4[..]].concat();
    let array: [u8; 32] = b32.try_into().unwrap();
    array.into()
}

fn signed(i: u32) -> RuntimeOrigin {
    let account_id = account_id(i);
    RuntimeOrigin::signed(account_id)
}

So ultimately, go and check your frame_system configuration and make sure your AccountId type is what you want and expect.